Niimbus US 5 PRO

Reference headphone & active-speaker amplifier with 256-step relay volume control

The Niimbus US 5 PRO is the refined successor to the acclaimed US 4 and US 4+ headphone amplifiers. It shares the core engineering of the US 5, while adding an ultra-precise 256-step volume control implemented via reed relays.

Enjoy a compact, outstanding-sounding headphone amplifier and a high-grade preamplifier in one unit. The sophisticated preamp function allows direct connection to power amplifiers or active speakers. Headphone and line outputs can be enabled/disabled separately from the front panel.

Premium multi-purpose design

A reference-class headphone amplifier plus a fully capable preamp stage: ideal for headphone rigs, power amps, or active speakers. Headphone and line outputs can be switched independently from the front.

Remote control

A beautifully machined, solid remote lets you control volume (256 steps), mute, input selection, plus headphone and line-out via infrared.

Technology highlights

• Perfect volume control: 256 precise steps via reed relays.
• Ultra-low noise: very low internal gain – self-noise is practically inaudible.
• High output voltage: ±50 V internal rails – ideal for high-impedance headphones.
• High output power: massive headroom – perfect for low-impedance and planar/magnetostatic headphones.
• High damping factor: extremely low output impedance for a strictly linear frequency response.

Features & connections

• 3 analog stereo inputs: 2× RCA (unbalanced), 1× XLR (balanced)
• Pre-Gain: –18 … +24 dB for perfect matching between source and headphones
• Motorized volume control and manual balance knob
• 4 amplifier stages: 7000 mW Pmax @50 Ω, 32 V RMS @600 Ω
• Headphone output monitoring (DC & clipping)
• Headphone and line outputs individually switchable
• Headphone outputs: 1× 4-pin XLR (bal.), 1× 4.4 mm Pentaconn (bal.), 2× 6.3 mm (1/4") (unbal.)
• Line-out: 1× RCA (unbal.), 1× XLR (bal.), adjustable level ±12 dB
• 2 toroidal transformers, > 50,000 µF filter capacitance

Package contents

• 1× Niimbus US 5 PRO
• 1× User Manual
• 1× Remote Control

Technical Data